Sewing machine



Aug. 31 1926.

A. F. LITTLEFlELD SEWING MACHINE Filed June 15, 1921 Patented Aug. 31, 1926.

UNHTE TA'lTES PTENT OFFICE,

AUGUSTINE F. LITTLEFIELD, O31 LYNN, MASSACHUSETTS, ASSIGNOR TO UNITED SHOE MACHINERY CORPORATION, OF PATTERSON, NEW JERSEY, A CORPORATION OF NEW JERSEY.

SEWING MACHINE.

Application filed June 15, 1921.

The present invention relates to sewing machines and more particularly to wax thread chain stitch inseam shoe sewing machines.

In the practical operation of sewing machines of this type, the operator in manipulating the shoe to disengage it from the machine, pulls a certain amount of thread from the supply through the stripper of the thread waxing device. In order that the thread tensioning devices of the machine may not interfere with such drawing of thread from the supply, means are usually provided for releasing the thread tensioning devices on stopping the machine. The thread stripper, however, offers consider able resistance to the travel of the thread and it has been found that the stripper cannot be tightened beyond a certain limit without causing it to furnish so much resistance to the travel of the thread that the seam will be unravellcd when it is attempted to draw the thread through the stripper during the removal of the shoe from the machine. VVith the stripper set as tight as is practicable and still permit such drawing of the thread from the supply, a great deal more wax than is necessary for satisfactory sewing is left on the thread after it passes through the stripper, and thus a large percentage of the wax is wasted. It has also been found that in the removal of the shoe a great deal more thread than is necessary is often drawn from the supply.

The principal object of the present invention is to provide means for overcoming the disadvantages above described.

lVith this and other objects in view a feature of the present invention contemplates the provision in a sewing machine of means for drawing a predetermined amount of thread from the supply to furnish slack thread for the removal of the work after the a sewing operation. The amount of thread thus drawn from the supply preferably is only sufficient to permit the work to be removed in the usual manner so that there is no danger of thread being wasted during the removal of the work. In the preferred embodiment of the invention the means for drawing thread from the supply operates independently of the movement of the work during its removal, so that with the use of this feature in a wax thread sewing machine Serial No. 477,817.

having a thread stripper, the drawing of the thread from the supply may be accomplished irrespective of the tightness of the stripper without danger of unravelling the seam.

Other features of the invention consist in certain constructions, arrangements and combinations of parts hereinafter described and claimed, the advantages of which will be obvious to those skilled in the art.

The several features of the invention will be clearly understood from the following description and accompanying drawings in which:

Figure 1 is a side elevation partly in section of the head of a Wax thread chain stitch inseam shoe sewing machine embodying the features in their preferred form; Fig. 2 is a detail sectional view taken on the line 22 of Fig. 1.

The machine illustrated in the drawings has the same general construction and mode of operation as the machine illustrated and described in the patent to Seely No. 1,240,-

094, dated Sept-ember 11, 1917. This machine is provided with a curved hook needle 2, a thread arm 4, a looper 6, a thread gripping and cutting device 8, a welt guide 10, a back rest or bunter 1,2, and a thread tension wheel 14. The thread gripping and cutting device 8 is mounted on the looper and is conveniently arranged to enable the thread extending between the stitch forming devices and the work to be inserted in the device and cut during the removal of the work. The thread tension wheel is secured to one end of a shaft 16 which extends through and is journaled in a pair of spaced bearings 18 formed on a bracket on the machine frame. In order to restrain the rotation of the shaft 16 to cause the tension wheel to exert the required amount of tension on the thread during the sewing operation, a brake drum 20 is secured to the shaft 16 between the bearings 18, the periphery of which is engaged by a springpressecl brake shoe 22. The brake shoe 22 is pivotally mounted on a lever 24 midway of its ends, which lever is pivotally mount ed at its forward end on the machine frame and is urged downwardly by a coiled spring 26 connected with its rear end. The machine which during the normal operation of the integral with the swinging arm '32.

this construction it will be apparent that suitable scribed are the same as the corresponding '32 engagcs-a-collar 3% carried by the shaft, but upon the reversal-otthe rotation of the driving shaft the arm 32 is shifted rearwardlyand its forward end is swung upwardly to bring a curved portion 36 thereof into engagement with the collar 34. Upon again starting the'machine the swinging arm 32 is moved to return-the curved portion 30 thereof into engagement with the collar 34:. The rear end of the swinging arm 32 is pivotally mounted on the upper end of a lever 38 pivoted at 4l0 on the machine frame, which lever upon reversal of*the rotation of the driving shaft is=actuated by the swinging arm 32 to retrac'tthe welt guide through connections. The parts above departs of the machine illustrated and described in the patent to Seely hereinbefore referred to,'to which reference may be had for a-completedescription of this and other parts of the machine not fully described herein.

In the-machine illustrated in'the drawings mechanism is provided for drawing a predetermined amount of thread from the supply upon stopping the machine, which amount of thread is sufficient to meet the requirements in the removal of the work.

As shown, this mechanism comprises the tension wheel ll and suitable connections through which it isrotated a-predetermined number of degrees by the swinging arm 32 uponstopping the machine. The connection between thetension wheel and the arm 82 comprises a grooved wheel or pulley 4:2 loosely mounted on one end of the tension wheel-shaft 16. A pair of diametrically opposed spring pressed pawls as are mounted on the outer faceof the pulley 42 which engage a ratchet wheel 46 secured-to the tension wheels'h'aft. The grooved periphery of "the pulley 4-2 is engaged by a chain or strap l7 having. one end connected with a coiled spring 48 secured tothe frame and its other end connected with the lower end of a rearwardly eii'tending depending arm o0 which is when the forward end of the arm 32' is swung upwardly to positionthe curvedpor- 'ilOIl 36thereof in engagement with the col- With lar 3i on the driving shaft upon the re versal in the direction of rotation of the shaft, the depending arm 50 will act through the strap l7 to rotate the pulley 42 a pre determined number of degrees in a cloc xwise direction. During'such rotation of the pulley 42 the ratchet and pawl connection between the pulley and the tension wheel shaft 16 will cause the tension wheel to be rotated with the pulley to draw thread from the supply. When the swinging arm 32 is swung downwardly to position the curved portion 30 thereof in engagement with the collarSl of the driving shaft upon-starting the machine into operation, the coiled spring l8'will be-permitted to.act through the strap 4:7 to return the pulley 42-t0its normal angular position. The ratchet and pawl connection between the pulley 42 and the shaft '16 permits such return movement of the pulley 4-2 independently of the tension wheeland shaft, and also permits the-operation of the tension wheel in the usual manner during the normal operation of the machine independently of the pulley 42 so that the mech anism does-not'inter fere with theoreration of thetension wheel during-the sewingoporation.

It will be apparent from the foregoing that the required amountof thread is drawn from the supply for the removalof thework without placing any strain on the stretch of thread extending from the thread tensio-ning devices to the work,-so that irrespective-of thetightness-of the thread stripping device there is no danger'of the seam being unravelled during the removal of the work. It will also be apparent that a mechanism for releasing the thread tension device on stopping the-machine, asis customaryin machines of this'tvpe, is unnecessary and the brake shoe 22 of the tension device may act uniforml atall times on the'tem sion wheel.

While the features described above are well adapted for use in a wax thread chain stitch inseam shoe sewing machine, it is to be understood than except asdefined in the claims, certain features of the invention are not limited to use in a sewing machine of this type.

The several features of the invention having been indicated and a machine embodying the features in their'preferred form having been specifically described,-what is claimed 1s:

1. A sewingonachine having, in combination, stitch forming devices,.a tension wheel over which the thread passes, and means for rotating the tension wheel Ia predetermined'number of degreesupon-stopping the machine acting at the-same'time to relieve the strain on th'e thread between the tension wheel and the work and to furnish :slaer thread for theremovalof the work.

2. A sewing machine having, in combination, stitch forming devices, a shaft, a tension wheel carried by the shaft over which the thread passes, a disk loosely mounted on the shaft, means for rotating the disk a predetermined number of degrees upon stopping the machine, and a ratchet and pawl connection between the disk and shaft to cause rotation of the tension wheel to draw thread from the supply upon stopping the machine and to permit rotation of the tension wheel independently of the disk upon a strain being placed on the thread.

3. A sewing machine having, in combination, stitch forming devices, a driving shaft for the machine driven in one direction during the sewing operation and in the reverse direction upon stopping the machine, and means actuated by the shaft upon rotation thereof in said reverse direction for drawing thread from the. supply to furnish slack thread for the removal of the work.

4. A sewing machine having, in combination, stitch forming devices, a driving shaft for the machine driven in one direction dur ing the sewing operation and in the reverse direction upon stopping the machine, thread tensioning devices, and connections between the threaded tensioning devices and the shaft for actuating said devices upon rotation of the shaft in said reverse direction for drawing thread from the supply to furnish slack thread for the removal of the work.

5. A sewing machine having, in combination, stitch forming devices, a driving shaft for the machine driven in one direction during the sewing operation and in the reverse direction upon stopping the machine, a thread tension wheel, and connections be tween the tension wheel and the driving shaft for rotating the tension wheel upon rotation of the shaft in said reverse direction for drawing thread from the supply to furnish slack thread for the removal. of the work.

6. A sewing machine having, in combination, stitch forming devices, a shaft, a tension wheel carried by the shaft, a pulley loosely mounted on the shaft, a ratchet and pawl connection between the pulley and the shaft to cause rotation of the tension wheel to draw thread from the supply upon rotation of the. pulley in one direction and to permit rotation of the tension wheel independently of the pulley upon a strain beingplaced on the thread, means for rotating the pulley in the direction to rotate the tension wheel comprising a strap in frictional engagement with the peripheral surface of the pulley, a spring connected with one end of the strap, a lever connected with the other end of the strap, and means for rocking the lever to rotate the pulley in said direction against the tension of said spring.

7 A sewing machine having in combination, stitch forming devices, a tension wheel, means for rotating the tension wheel a predetermined number of degrees upon stopping the machine acting at the same time to relieve the strain on the thread between the tension wheel and the work and to furnish slack thread from the supply for the removal of the work, and a brake for restrain ing the rotation of the tension wheel to exert a uniform force on the wheel during the sewing and work removing operations.

8. A sewing machine having, in combination, stitch forming devices, a thread tension wheel, and means for rotating the tension wheel a predetermined number of degrees after the sewing operation to draw thread from the supply while relieving the strain on the thread between the tension wheel and the work.

9. A sewing machine having, in combina tion, stitch forming devices, a tension wheel over which the. thread passes, a cam shaft, and a train of mechanism actuated from the cam shaft and forming a. permanent part of the machine for rotating the tension wheel a predetermined number of degrees upon stopping the machine to furnish slack thread for the removal of the work.

AUGUSTINE F. LITTLEFIELD. 

